Are you ready for the dark side?

Over the past few days, I’ve come across four articles published between the 20th and 24th of December as a timely prelude to the annual chocolate glut. All reported that a recent scientific study had demonstrated that the cycling performance of tests subjects improved after two weeks of eating 40 g of dark chocolate daily, as opposed to a group who’d eaten 40 g of white chocolate.

Now, our household doesn’t really buy into the latest food fads, but this was different, we were talking chocolate! So my initial reaction was joy, who doesn’t like chocolate? But the Jedi in me wanted to better understand how to reap the benefits mentioned in the study. My main question at the time was along the lines of “Yes, 40 g of dark chocolate eat you shall but… what is it that “dark”, you call? In terms of cocoa percentage? “

It was itself published just before the Christmas craze, which made me wonder at the sense of timing editors of scientific journals can show.

I greedily read the article, looking for answers to life and the universe, namely:

Who were the test subjects ?

There were 9 volunteers, all male and around 21 years old. The study was conducted at Kingston University, so I deducted that some lucky students got free chocolate for two weeks! That’s fine but a question remains: were there no female who liked chocolate? Female and male physiology is not always comparable from what I understand so having representatives of both sexes would have definitely made it more applicable to little me. Despite their youth and health, the test subjects were not elite athletes, but described as “moderately trained”. So how applicable is it to the older people on the planet? Now that the ground breaking stuff is out, I’d love to see studies focusing on all ages and on women too.

2. What dark chocolate did they eat?

Doves Promises Dark (Mars), which is a regular protagonist in scientific studies of dark chocolate but isn’t available in the UK. That really gave me some food for thought: what is it that makes Doves Dark so interesting?

3. What were the benefits and how were they measured?

This is what I take away from the research

VO2 max

After two weeks, the VO2 max of the dark chocolate eaters was 6% higher than it had been at the start and also 6% higher than that of the unlucky guys who ate white chocolate. A big difference that actually fails to meet the holy grail of scientific studies: statistical significance. Almost certainly because of the small sample size.

Blood pressure

The dark chocolate eaters’ blood pressure was 6% lower than it had been at the start and than that of the white chocolate eaters (again, not statistically significant, see above).

Gas Exchange Threshold

The GET of the dark chocolate eaters was 21% higher (and statistically significant) than it had been at the start of the study and 11% higher (borderline statistically significant) than that of the white chocolate eaters.

Oxygen consumption and respiratory exchange ratio

Dark or white chocolate made no difference to either of these variables

Distance covered in a 2 minute time trial at the end of a moderate 20 minute ride

The dark chocolate eaters rode 17% farther at the end of the study, and 13% farther than the white chocolate eaters. (both statistically significant)

Applicability to triathlon training: dark chocolate (well, Dove Dark) looks promising if you want to push the limits of your VO2 max, GET and cycle further. Hey, I want some of this!

Tell us your secret, who’s your father?

Dove’s secret ingredient: epicatechin

I searched, there is no reasonably priced Dove Dark chocolate in the UK. In fact the only products that my favourite supermarkets stock under the name “Dove” are toiletries. So I looked in more details at what might be driving these performance improvements. I learned that it’s attributed to epicatechin, a flavonol in cocoa beans that is thought to improve the bio-availability of nitric oxide (the stuff that took beetroot juice to the tour de France’s peloton) thus improving vasodilation, glucose uptake, muscular contraction and making you go faster longer.

There is a vast amount of scientific literature vouching for the health benefits of epicatechin, notably in all things cardiovascular but I particularly like another study where it apparently increased the running ability of lab rats bred for their low running capacity, now that sounds interesting too…

Why darker is not necessarily better

Not one to give up, I set off in search of the ideal chocolate, with high levels of epicatechin, just like Dove. Surely chocolates with high a cocoa contents are good contenters. Disappointingly, that’s not necessarily true: in the 19th Century, Mr Van Houten, invented a process now called dutching where cocoa powder undergoes a treatment that darkens its colour and makes it less bitter. Mr T now calls Van Houten the “frying Dutchman” as unfortunately dutching also removes up to 98% of epicatechin, fermentation and roasting are also not ideal The best treatment to preserve epicatechin is drying and the origin of the beans also plays a role.

Note to self: all dark chocolate is not created equal

Nightmare! How can I intelligently include cocoa products in my training? Yes, obviously, I could just enjoy the thing but why not get the most bang for my (calorific) buck?

Then, I discovered a study that looked at the flavonoids present in commercial cocoa products. HURRAY!

The authors named the products they analysed (three or four in each of 6 categories ranging from cocoa powder to chocolate syrup) but did not assign results to a particular product name, choosing to rank the categories rather than the products. The highest in epicatechin were:

Both categories had much higher counts of epicatechin than the next category of dark chocolate (Hershey’s Special Dark, Lindt Excellence 70% Cocoa and the scientists’ favourite: Dove Dark). Assuming Dove Dark has got the highest content of epicatechin of the three dark chocolates tested (0.605 mg/g), 40 g of Dove Dark would amount to 24.2 mg.

Where do I find that? The only brand I found that had their chocolates tested (by an independent lab) was Green & Black’s . Results below:

I also calculated a rough price for 11g of G&B’s cocoa: it’s just under 15 p.

Theobroma cacao in a cup

I’m now considering giving up coffee in favour of cocoa, complete with added chili or vanilla.

Not just because of the epicatechin: I discovered that cocoa contains theobromine, an alkaloid related to caffeine and with similar effects. Theobromine has numerous cardiovascular benefits and has been shown to increase the endurance of untrained rats (again!) who ran longer before exhaustion when they had consumed theobromine. Although, like most things, theobromine is poisonous in large doses (although for a fatal dose you would need to eat more than 5 kg of milk chocolate), but a daily dose of 50-100 g of cocoa could give you nausea. I’m happy to take the risk.

So, if like 100% of the cycling/running/triathleting population your New Year resolution is to improve your VO2 max, stay lean and get better at what you’re doing and if you want to see for yourself whether chocolate can help, your best option might be the dark stuff.

I’m now heading for the shops to purchase G&B’s super power cocoa powder. From now on I will drink my daily hot cocoa dutifully prepared with 2 tablespoons of it in either water or hazelnut milk. I’ll let you know in 6 weeks what the dark force has done. Anyone else want to join the trial?